Epidemiology of invasive Haemophilus influenzae serotype a disease in the North American Arctic, 2006–2017

Figures & data

Figure 1. (a) Reported cases of non-b encapsulated invasive Hi disease by serotype, Alaska, 2006–2017. (b) Reported cases of non-b encapsulated invasive Hi disease by serotype, Northern Canada, 2006–2017.

Table 1. Characteristics of Alaskan and Northern Canadian persons with invasive Hia disease, 2006–2017.

Characteristic	Alaska (n=53)	N. Canada (n=111)
Median age in years (min-max)	0.9 (0.1–76.8)	1.4 (0.1–80)
Sex, male, # (%)	33 (62)	58 (52)
^1Indigenous, # (%)	48 (91)	107 (96)
^2Age appropriately vax for Hib, # (% vax)	45 (94)	69 (95)
^3Hospitalized, # (%)	46 (87)	94 (90)
^4Deaths, # (%)	6 (11)	10 (10)

¹Ethnicity missing/unknown for 1 case in N. Canada

²Vaccine history missing from 1 case in Alaska; denominator=48

Vaccine history missing from 9 cases in N. Canada; denominator=73

³Hospitalization data missing for 5 cases in N. Canada

⁴Death data missing/unknown for 11 cases in N. Canada

Table 2. Cases and annualised incidence rate of invasive Hia disease by age and ethnicity, 2006–2017.

Demographic group	Alaska, # cases (rate)^1	N. Canada, # cases (rate)^1
Overall	53 (0.6)	111 (6.0)
<2 years	44 (16.9)	73 (109.8)
<5 years	49 (7.5)	82 (50.1)
Overall, Indigenous	48 (2.8)	107 (9.5)
<2 years, Indigenous	42 (56.2)	72 (144.1)
<5 years, Indigenous	45 (24.4)	81 (64.8)
Overall, non-Indigenous	5 (0.1)	3 (0.4)
<2 years, non-Indigenous	2 (1.1)	1 (6.1)
<5 years, non-Indigenous	4 (0.9)	1 (2.6)
Overall, Indigenous v non-Indigenous	p<0.001	p<0.001
<2 years, Indigenous v non-Indigenous	p<0.001	p<0.001
<5 years, Indigenous v non-Indigenous	p<0.001	p<0.001

¹Cases per 100,000 population

Table 3. Clinical illnesses¹ in Alaska and Northern Canada persons with invasive Hia by age, 2006–2017.

Illness	Alaska		N. Canada^2
	<5 years (n=49), # (%)	≥5 years (n=4), # (%)	<5 years (n=82), # (%)	≥5 years (n=29), # (%)
Meningitis	22 (45)	0 (0)	22 (27)	2 (7)
Pneumonia	12 (25)	1 (25)	20 (24)	13 (46)
Cellulitis	8 (16)	1 (25)	3 (4)	3 (11)
Septic arthritis	8 (16)	0 (0)	14 (17)	3 (11)
Bacteraemia	4 (8)	2 (50)	21 (26)	8 (28)
Osteomyelitis	2 (4)	0 (0)	1 (1)	0 (0)
Other^3	2 (4)	0 (0)	2 (2)	1 (4)

¹Cases may have multiple illnesses associated with Hia infection.

²10 Northern Canada cases are missing clinical diagnosis data.

³Other includes Empyema, unknown and “Other”.

Figure 2. (a) Sequence type results for invasive Hia strains, Alaska, 2006–2017. (b) Sequence type results for invasive Hia strains, Northern Canada, 2006–2017.